Detection of magnetic field in the B2 star ρ\rho Oph A with ESO FORS2

Circumstantial evidence suggests that magnetism and enhanced X-ray emission are likely correlated in early B-type stars: similar fractions of them ($\sim$ 10 %) are strong and hard X-ray sources and possess strong magnetic fields. It is also known that some B-type stars have spots on their surface. Yet up to now no X-ray activity associated with spots on early-type stars was detected. In this Letter we report the detection of a magnetic field on the B2V star $\rho$ Oph A. Previously, we assessed that the X-ray activity of this star is associated with a surface spot, herewith we establish its magnetic origin. We analyzed FORS2 ESO VLT spectra of $\rho$ Oph A taken at two epochs and detected a longitudinal component of the magnetic field of order of $\sim500$ G in one of the datasets. The detection of the magnetic field only at one epoch can be explained by stellar rotation which is also invoked to explain observed periodic X-ray activity. From archival HARPS ESO VLT high resolution spectra we derived the fundamental stellar parameters of $\rho$ Oph A and further constrained its age. We conclude that $\rho$ Oph A provides strong evidence for the presence of active X-ray emitting regions on young magnetized early type stars.Comment: 4 pages, 1 figure, 2 tables, accepted as a "Letter to the Editor" to Astronomy & Astrophysic

The 2011 October Draconids Outburst. II. Meteoroid Chemical Abundances from Fireball Spectroscopy

On October 8, 2011 the Earth crossed dust trails ejected from comet 21P/Giacobini-Zinner in the late 19th and early 20th Century. This gave rise to an outburst in the activity of the October Draconid meteor shower, and an international team was organized to analyze this event. The SPanish Meteor Network (SPMN) joined this initiative and recorded the October Draconids by means of low light level CCD cameras. In addition, spectroscopic observations were carried out. Tens of multi-station meteor trails were recorded, including an extraordinarily bright October Draconid fireball (absolute mag. -10.5) that was simultaneously imaged from three SPMN meteor ob-serving stations located in Andalusia. Its spectrum was obtained, showing a clear evolution in the relative intensity of emission lines as the fireball penetrated deeper into the atmosphere. Here we focus on the analysis of this remarkable spectrum, but also discuss the atmospheric trajectory, atmospheric penetration, and orbital data computed for this bolide which was probably released during 21P/Giacobini-Zinner return to perihelion in 1907. The spectrum is discussed together with the tensile strength for the October Draconid meteoroids. The chemical profile evolution of the main rocky elements for this extremely bright bolide is compared with the elemental abundances obtained for 5 October Draconid fireballs also recorded during our spectroscopic campaign but observed only at a single station. Significant chemical heterogeneity between the small meteoroids is found as we should expect for cometary aggregates being formed by diverse dust components.Comment: Manuscript in press in Monthly Notices of the Royal Astronomical Society. Accepted for publication in MNRAS on April 28th, 2013 Manuscript Pages: 28 Tables: 5 Figures: 12. Manuscript associated: "The 2011 October Draconids outburst. I. Orbital elements, meteoroid fluxes and 21P/Giacobini-Zinner delivered mass to Earth" by Trigo-Rodriguez et al. is also in press in the same journa

Life cycle assessment of low-cost technologies for digestate treatment and reuse in small-scale farms in Colombia

Anaerobic digestion (AD) is a practice that is mainly carried out to give treatment to different kinds of organic residues (e.g. food waste, manure, agricultural residues) in order to obtain biogas and produce bioenergy. Because of its nature, the generated biogas is considered to be a renewable energy source, henceforth an important strategy in the fight against climate change. Anaerobic digesters carry out the AD process under specific conditions to allow microbial communities to develop and decompose organic matter (OM) into the desired biogas. In addition to biogas, the degradation of organic waste in the digester also produces a liquid effluent (digestate) (U.S. EPA, 2021). This exiting digestate is a combination of solid and liquid fractions from the AD process, rich in nutrients and OM. Because of its characteristics, digestate is a valuable effluent, as it can be used as organic fertilizer and spread on agricultural lands (Panuccio, et al., 2018). The use of digestate as fertilizer has several benefits, such as boosting crop growth and quality, acting as soil amender, or mitigating greenhouse gas (GHG) emissions (Wang & Lee, 2021). Nonetheless, depending on the characteristics of the feedstock and on the further use of the digestate, it has to undergo treatment and/or stabilization to avoid the spreading of pathogens, toxic metals or other pollutants that might be present in it (Cucina et al., 2021; Wang & Lee, 2021). For this study, this rationale has been implemented in Colombian low-income small-scale farms. Colombia is a country with a great agricultural tradition, considering that by 2017 more than 15% of the domestic extraction of the country was related to the agricultural industry (Material Flows, 2019). Nevertheless, even though Colombia has expected a considerable growth throughout the past 30 years, up to 50% of its population is considered to live in poverty (Garfí, et al., 2019). Consequently, low income populations have to rely on self-sufficient farming and traditional fuels such as firewood and dry dung for cooking and house warming. For these reasons, low-cost digesters have been implemented in several Colombian communities to cope with homely energy demands and substitute the risky traditional fuels that end up affecting both people and the local environment (Garfí, et al., 2011). It is in this context that several studies have been carried out to analyze the environmental performance of anaerobic digesters in rural conditions in the Andes (Garfí, et al., 2012; Garfí, et al., 2019; Mendieta, et al., 2021). However, these studies have focused on the implementation of the digester and the biogas use, but have not deepened in the treatment and use of the digestate. Even though these studies have considered a direct use of digestate, other authors have stated that, despite the benefits of this practice, it might have associated risks if no further treatment of the digestate is carried out prior to its application on land (Cucina, et al., 2021). Therefore, the main objective of this study is to analyze the environmental impacts of three alternative scenarios for the digestate treatment and reuse from a low-cost anaerobic digester: 1) digestate treatment with a sand filter and its reuse as biofertilizer 2) digestate treatment with a vermifilter and its reuse as biofertilizer; 3) a baseline scenario without digestate treatment (direct use on land).The research was funded by the Centre for Development Cooperation (CCD) of the Technical University of Catalonia (UPC) (CCD2021-J004), the Universidad Industrial de Santander, Colombia (Proyecto 2504), and the Ministry of Science and Technology of Colombia (Contrato número 583-2020). Marianna Garfí are grateful to the Government of Catalonia (Consolidated Research Group 2017 SGR 1029), and to the Spanish Ministry of Economy and Competitiveness (RYC-2016 20059).Postprint (published version

Oxidative stability of functional phytosterol-enriched dark chocolate

A dark chocolate containing phytosterols (PS) esters was developed to reduce cholesterol in individuals. However, oxidative instability during chocolate processing and storage could reduce the PS bioactivity. Chocolate bars were prepared containing palm oil (CONT) or 2.2 g of PS (PHYT). All samples were stored at 20°C and 30°C during 5 months. A peak of hydroperoxides formation was observed after 60 days at 20°C and after 30 days at 30°C. PS-enriched samples presented higher values of hydroperoxides than control samples, which could be attributed to the higher level of alpha-linolenic acid present in the PHYT samples. All chocolate bars became lighter and softer after 90 days of storage. However, these physical changes did not reduce their sensory acceptability. In addition, PS bioactivity was kept during the storage, since no significant alterations in the PS esters were observed up to 5 months. However, some PS oxidation occurred in the PHYT bars, being sitostanetriol, 6-ketositosterol, 6beta-hydroxycampesterol and 7-ketocampesterol the major phytosterol oxidation products (POPs). The POPs/PS ratio was low (0.001). Therefore, the dark chocolate bars developed in this study kept their potential functionality after 5 months of storage at room temperature, representing an option as a functional food

Long-term multi-wavelength studies of GRS 1915+105 I. A high-energy and mid-infrared focus with RXTE, INTEGRAL, and Spitzer

To date, mid-infrared properties of Galactic black hole binaries have barely been investigated in the framework of multi-wavelength campaigns. Yet, studies in this spectral domain are crucial to get complementary information on the presence of dust and/or on the physical processes such as dust heating and thermal bremsstrahlung. Here, we report a long-term multi-wavelength study of the microquasar GRS 1915+105. On the one hand, we aimed at understanding the origins of the mid-infrared emission, and on the other hand, at searching for correlation with the high-energy and/or radio activities. We observed the source at several epochs between 2004 and 2006 with the photometer IRAC and spectrometer IRS, both mounted on the Spitzer Space Telescope. When available, we completed our set of data with quasi-simultaneous RXTE and INTEGRAL high-energy and/or Ryle radio observations from public archives. We then studied the mid-infrared environment and activities of GRS 1915+105 through spectral analysis and broad band fitting of its radio to X-ray spectral energy distributions. We detected polycyclic aromatic hydrocarbon molecules in all but one IRS spectra of GRS 1915+105 which unambiguously proves the presence of a dust component, likely photoionised by the high-energy emission. We also argue that this dust is distributed in a disc-like structure heated by the companion star, as observed in some Herbig Ae/Be and isolated cool giant stars. Moreover, we show that some of the soft X-ray emission emanating from the inner regions of the accretion disc is reprocessed and thermalised in the outer part. This leads to a mid-infrared excess that is very likely correlated to the soft X-ray emission. We exclude thermal bremsstrahlung as contributing significantly in this spectral domain.Comment: 46 pages, 6 tables, 6 figures, accepted in Ap

Blackwater fever in a non-immune patient with Plasmodium falciparum malaria after intravenous artesunate

Blackwater fever was typically reported after quinine administration, although it is poor recognized in patients receiving artesunate. This case describes a blackwater fever in a non-immune patient after artesunate for severe malaria. It highlights the importance of monitoring haemolytic parameters in severe malaria to avoid renal impairment or severe anaemia

Characterizing a new class of variability in GRS 1915+105 with simultaneous INTEGRAL/RXTE observations

We report on the analysis of 100 ks INTEGRAL observations of the Galactic microquasar GRS 1915+105. We focus on INTEGRAL Revolution number 48 when the source was found to exhibit a new type of variability as preliminarily reported in Hannikainen et al. (2003). The variability pattern, which we name $\xi$, is characterized by a pulsing behaviour, consisting of a main pulse and a shorter, softer, and smaller amplitude precursor pulse, on a timescale of 5 minutes in the JEM-X 3-35 keV lightcurve. We also present simultaneous RXTE data. From a study of the individual RXTE/PCA pulse profiles we find that the rising phase is shorter and harder than the declining phase, which is opposite to what has been observed in other otherwise similar variability classes in this source. The position in the colour-colour diagram throughout the revolution corresponds to State A (Belloni et al. 2000) but not to any previously known variability class. We separated the INTEGRAL data into two subsets covering the maxima and minima of the pulses and fitted the resulting two broadband spectra with a hybrid thermal--non-thermal Comptonization model. The fits show the source to be in a soft state characterized by a strong disc component below ~6 keV and Comptonization by both thermal and non-thermal electrons at higher energies.Comment: Accepted for publication in A&A. 11 pages, 10 figures, 4 in colour. Original figures can be found at http://www.astro.helsinki.fi/~diana/grs1915_rev48. Author affiliations correcte